Bob I agree that ESD or FXY[E] appear to be the best units to use, but you can't always dictate which format you receive your data in... So with the STD format, the total number of counts for a point is given by counter*intensity and the esd is given by sqrt(intensity/counter)? Also, going on with your comment about the FXYE format, is TOFT still centidegrees*32 (as per the manual) or just plain centidegrees?
Cheers Matthew ________________ Matthew Rowles CSIRO Minerals Box 312 Clayton South, Victoria AUSTRALIA 3169 Ph: +61 3 9545 8892 Fax: +61 3 9562 8919 (site) Email: matthew.row...@csiro.au ________________________________ From: Brian H. Toby [mailto:brian.t...@anl.gov] Sent: Tuesday, 17 March 2009 00:31 To: vondre...@anl.gov Subject: Re: GSAS data formats I don't think this went to the mailing list On Mar 16, 2009, at 7:44 AM, Robert Von Dreele wrote: Hi, Brian is correct in that the 'FXYE' format is "best" as it is the simplest to implement. It requires 3 columns of data in free format (either floating point or exponental forms are OK). 1st column is position (in centidegrees), 2nd is intensity (corrections can be applied if needed) & 3rd is esd (error propagation for corrections applied here). The STD format is no. counters & intensity. The intensities are all on same basis i.e. the average over the number of counters used to collect that point. GSAS calculates the esd (& weight) using the number of detectors. BTW - the GSAS Manual indicated that records need be 82 characters long. This is no longer true. Records can be shorter. Best, Bob Von Dreele ----- Original Message ----- From: "Brian H. Toby" <brian.t...@anl.gov> Date: Monday, March 16, 2009 0:30 am Subject: Re: GSAS data formats To: matthew.row...@csiro.au Cc: rietveld_l@ill.fr I do not recommend using this format. Better choices are the ESD variant on this, where numbers are alternated intensity, esd, intensity... (and there are a lot more digits for each number) or the FXYE format, which has angle, intensity, and optionally esd, one entry per line in free format. My recollection on this is that YO is the total number of counts, so the normalized Intensity = YO/n and the error on that is SQRT(YO)/n. The idea being that not all measurements are made with the same number of detectors. Brian On Mar 16, 2009, at 12:02 AM, matthew.row...@csiro.au wrote: Hi all I'm going over the GSAS data format (by reading the manual), trying to figure out how it works, and I've come up with a couple of questions: 1) In a STD data set, the manual says that NCTR is the number of counters and YO is the n number of counts per counter. So, for a single data point " 3 3452", is the total counts =3*3452? What is the error? Sqrt(3*3452), 3*sqrt(3452) or sqrt(3452/3)? 2) What is the data format for type = "ALT"? The manual (http:// www.ccp14.ac.uk/ccp/ccp14/ftp-mirror/gsas/public/gsas/manual/ GSASManual.pdf) doesn't say... Cheers Matthew ________________ Matthew Rowles CSIRO Minerals Box 312 Clayton South, Victoria AUSTRALIA 3169 Ph: +61 3 9545 8892 Fax: +61 3 9562 8919 (site) Email: matthew.row...@csiro.au ******************************************************************** Brian H. Toby, Ph.D. office: 630-252-5488 Senior Physicist/Materials Characterization Group Leader Advanced Photon Source 9700 S. Cass Ave, Bldg. 433/D003 work cell: 630-327-8426 Argonne National Laboratory secretary (Marija): 630-252-5453 Argonne, IL 60439-4856 e-mail: brian dot toby at anl dot gov ******************************************************************** "We will restore science to its rightful place, and wield technology's wonders... We will harness the sun and the winds and the soil to fuel our cars and run our factories... All this we can do. All this we will do." ******************************************************************** Brian H. Toby, Ph.D. office: 630-252-5488 Senior Physicist/Materials Characterization Group Leader Advanced Photon Source 9700 S. Cass Ave, Bldg. 433/D003 work cell: 630-327-8426 Argonne National Laboratory secretary (Marija): 630-252-5453 Argonne, IL 60439-4856 e-mail: brian dot toby at anl dot gov ******************************************************************** "We will restore science to its rightful place, and wield technology's wonders... We will harness the sun and the winds and the soil to fuel our cars and run our factories... All this we can do. All this we will do."
